evaluation of [sun protection factor] SPF accuracy of some sunscreens

ABSTRACT

The prevalence of photo-aging and skin cancers has been increasing in many parts of the world. To reduce cutaneous photodamage and skin carcinogenesis, primary prevention that an integral component of it is the use of sunscreens is recommended. The aim of this study was assessment of SPF accuracy in some Iranian sunscreens. Among healthy individuals with skin types I to III, 25 volunteers enrolled, but finally ten persons for two sunscreens "X" and "Y" completed the study. Candidates were tested during three days using phototherapy UV 800 K with UV B lamps, UV skin-tester and UV-meter [Waldman Company, Germany]. Minimal erythemal dose in unprotected areas of the skin [MEDup] was initially measured and then in protected areas [MEDp] was determined, according to the MEDup amount and national sunscreens' SPF label [SPF30]. Volunteer was exposed to his own MEDp and also 85% of it, after 24 hours, the two areas were examined for erythema. The final test result declared "correct", for the tested cream, if the accuracy of the SPF was confirmed in at least 90% of volunteers. The accuracy of test was confirmed according to SPF assessment standard protocol. All the candidates were male with mean age of 33.5 +/- 8.51 yrs. The MED mean was 73/09 +/- 15/6 mj/cm2. Final results declared "correct" for both products. In addition, the standard lotion test result was correct for all candidates. According to the results, we can assure people and physicians about reliability of labeled SPF, at least in some of the national products